Laat time I checked Investing or buying at the top is never a good idea, cause you might buy and the next thing the coin will start dumping massively, let's use the 2017 bull run for example, the people who bought bitcoin at the top back then had to wait good 3yrs before the price returned back to the ATH, anyway investments are risky you can never tell what might happen next, but the best advice I can give is to buy when it's cheap not at the top, it's just too risky but if you are up for the risk then go ahead.